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An anonymous reader writes "One of the major ways a semiconductor manufacturer manages to make the most of its chips is through binning. Chips able to cope with high clock speeds with all cores running end up as premium product lines, while others end up as models rated at lower speed grades, or with fewer cores. In the case of AMD's Phenom CPUs, dual and triple core models are quad cores with some disabled, while some newer quad core CPUs are actually six core models with two disabled. To this end both ASUS and MSI have announced that they have modified versions of AMD 890FX- and 890GX-based motherboards to unlock these hidden cores. Much like overclocking, there is no guarantee that you will gain anything by unlocking the hidden cores — everything depends on just why your CPU ended up in a certain product line."

You're showing a complete lack of understanding as to how processors are rated and sold. AMD determines they need to meet a certain quota for each model of CPU. If it works out and all of the CPUs in their 1 million unit run works flawlessly, they will maximize their profit by disabling some of them and selling them for less money to account for that market without flooding the market with their top performing part.

Unless this is a rehash of when Intel were (alleged?) to be selling 486DX processors as 486SX with perfectly good maths co-processor cores disabled...

You're showing a complete lack of understanding as to how processors are rated and sold. AMD determines they need to meet a certain quota for each model of CPU. If it works out and all of the CPUs in their 1 million unit run works flawlessly, they will maximize their profit by disabling some of them and selling them for less money to account for that market without flooding the market with their top performing part.

True, but there's also a good possibility that the your part wasn't binned to fulfill an order. Chips go through a severe set of stress tests that often exceed what will be encountered in practical use. During these tests, it may be revealed that a core doesn't function properly or well enough (it gives bad results) to qualify. All chips go through that, and that's why there's many redundant structures on a chip (to improve yields). (Sony PS3 has 7 SPUs when they build 8 on a chip, Xbox360's got 3 PowerPC cores even though it has 4, Intel disables cache lines and/or functional units, etc. etc. etc.)

So the question is, are those cores disabled because AMD had extra parts and an outstanding order they could fulfill? Or are there actually potential issues that may only be revealed under certain loads? FOr the most part, it just means a game crashes a bit more often than usual (since mission critical servers never do wierd things like this - the money saved isn't worth the potential for extra downtime), or maybe a file gets corrupted. Or worse, your disk gets corrupted.

Plus, AMD's historically been supply-bound and unable to fulfill demand for their product, so there's a potential that instead of getting a binned part, it's actually one that failed their test patterns.

And yes, you see the same behavior with flash chips - NAND flash traditionally ships with bad blocks, and the majority of those can probably be erased and used quite safely (having accidentally destroyed the bad block information before due to buggy software...), but you never can tell why it was marked bad in the first place.

The problem is you don't know if a particular core was disabled for legitimate flaws or for marketing. From AMD's standpoint, they probably don't want to disable the cores unless there was not other choice than they really needed to fill orders because they can sell the fully functional chip for lots more money.

That's why you test the core. If you have the knowledge of being able to turn on a core, you have the knowledge telling you that you should stress test it with prime95 or somesuch.Argue this fact as much as you like, if you're the idiot who didn't check for stability it's your own damn fault.

And this information has been out for a long time and slashdot is just now finding out?

Granted, it does directly or indirectly stress the fpu, cache, maybe task switching and interrupt handling. However, there are many more things that can go wrong.

Off the top of my head, I can think of a lot of things that specifically need tested that one program probably won't do. For example, you need to verify both 32-bit and 64-bit operations. Prime95 is specifically compiled for one or the other, so would stress less of the "other" version.

There are also a lot of SIMD [wikipedia.org] instructions that need tested. Some are obscure enough that only a few apps would use them.

Then, there's all the instructions that support virtualization. I have found that bad hardware running a hypervisor will fail much more frequently than if it is running a "normal" OS (YMMV).

But, unlike Memtest86+ [memtest.org] for RAM, there doesn't appear to be any program that specifically tests all CPU subsystems (registers, cache, instruction execution, etc.).

To be fair, I don't know of a better way to test, and I'd love to see a discussion of better utilities. If I tried this I'd probably do mprime and keep an eye out for MCE's in the system logs, but don't delude yourself into thinking that core is error free because you ran prime95.

There are quite a few tools, mainly found in the overclocking communities. OCCT [guru3d.com], Linx [xtremesystems.org] and Intel Overburn [intel.com] just to name some.

You're showing a complete lack of understanding as to how processors are rated and sold. AMD determines they need to meet a certain quota for each model of CPU. If it works out and all of the CPUs in their 1 million unit run works flawlessly, they will maximize their profit by disabling some of them and selling them for less money to account for that market without flooding the market with their top performing part.

True, but there's also a good possibility that the your part wasn't binned to fulfill an order. Chips go through a severe set of stress tests that often exceed what will be encountered in practical use. During these tests, it may be revealed that a core doesn't function properly or well enough (it gives bad results) to qualify. All chips go through that, and that's why there's many redundant structures on a chip (to improve yields). (Sony PS3 has 7 SPUs when they build 8 on a chip, Xbox360's got 3 PowerPC cores even though it has 4, Intel disables cache lines and/or functional units, etc. etc. etc.)

So the question is, are those cores disabled because AMD had extra parts and an outstanding order they could fulfill? Or are there actually potential issues that may only be revealed under certain loads? FOr the most part, it just means a game crashes a bit more often than usual (since mission critical servers never do wierd things like this - the money saved isn't worth the potential for extra downtime), or maybe a file gets corrupted. Or worse, your disk gets corrupted.

Plus, AMD's historically been supply-bound and unable to fulfill demand for their product, so there's a potential that instead of getting a binned part, it's actually one that failed their test patterns.

And yes, you see the same behavior with flash chips - NAND flash traditionally ships with bad blocks, and the majority of those can probably be erased and used quite safely (having accidentally destroyed the bad block information before due to buggy software...), but you never can tell why it was marked bad in the first place.

I bought a Ph2 720BE and unlocked it to a quad. Stress tested with 12 hours of Prime95, no failures. When the core is bad, you usually can't even boot into Windows; never have I heard of one that could withstand gaming for more than 5 seconds. If something in it is broken, you know it.

So I paid $120 back when the Ph2 965 cost $240, and unlocked and overclocked the 720BE I bought to a quad at 3.5ghz. 4 cores for the price of 3. Love it.

If a core is just flat out non-functional then yes, you are right, a system wouldn't boot. However that it works mostly doesn't mean there isn't a problem. There could be a single instruction that has a flaw, so everything is fine unless that instruction gets executed but when that happens you get a crash or worse, data corruption.

If you think Prime95 is an accurate test, you are kidding yourself. Prime95 tests the FPU mainly, and is good for heat testing. It is not a full CPU test. So maybe the FPU works great, but one of the other units doesn't.

So no, you don't know that nothing is broken. You assume nothing is broken. Maybe that's fine, however then no bitching if you get data corruption or the like because there was a problem that you didn't know about.

Okay, not only are the disabled cores (and their local caches) sometimes tested to fail, sometimes they are NOT TESTED AT ALL. If the production run says we're only going to have 3 out of 4 possible cores (with cache), they're not going to bother testing the fourth core (and its cache) if the first three test successfully. Worse, if they're calling for 2 cores out of 4, they test and get two good ones and DO NOT TEST the third and fourth core.

If the production run says we're only going to have 3 out of 4 possible cores (with cache), they're not going to bother testing the fourth core (and its cache) if the first three test successfully. Worse, if they're calling for 2 cores out of 4, they test and get two good ones and DO NOT TEST the third and fourth core.

You don't seem to realize how the economics of this really works out. Nobody will set up a production run before hand and say "this line only needs to produce 3 usable cores". Nobody will do this because no fabrication process has 100 % yield... in fact, most cutting-edge runs have far less.

Let's say your fabrication process produces 1M chips per run, and we have the capacity to do 2 runs at once. You set up a '2-core' run, and find that 95% (950k) of the results have two working cores. Well, that seems great, now you can sell this 95 % at your bargain bin price. However, your '4-core' run may have had a yield of only 40 % (400k)... now, you have to spend more time and money producing more 4-cores to meet demand (lets say... 750k each), while you are selling perfectly good 4-cores at a 2-core price.

Instead, all of the chips will be fabricated and tested at a 4-core 'level'. If 1 core fails, put it in the 3-core bin. If 2 cores fail, put it in the 2-core bin. If your yield was better than you expected, then you can bump some 4-cores down to the lower bins to meet demand. If your yield was poor, you are drawing from a much larger sample of chips (2M, so 40 % yield --> 800k 4-cores), so you don't have to produce more to fill the demand!

and that's why I made the comments about the games. Prime95 is not the only stability test I ran, lol, duh.

All my applications work fine; I've been running this rig for about 8 months now.I don't know why you're so hell-bent on telling me my chip is broken, people get pissed when someone gets something for free it seems...we should tax me since I didn't pay for it.

You are clearly cheating in the e-Penis tests, everybody knows you have to spend more money in order to brag about your kickass hardware, otherwise, you will be labeled as a smart consumer which is not compatible with the 1337woopassHardwarez0wnzorzx label.:)

Good work! I plan to do something similar soon, though the cost savings of getting a $100 2-core Ph2 and unlocking it to a $160 4-core Ph2 isn't so great:/

I'll share my pseudo-failure story, though. I bought a Tyan Tiger MPX about 10 years ago to run dual SMP 1Ghz Durons. About 5 years later I upgraded the CPUs to 2.0 Ghz mobile Athlon XP. My motherboard couldn't control the mobile chips, so I think they only ran at 1.2Ghz or something for a time, then I got brave and whipped out the xacto knife and cut some bridges to clock them up to 1.8Ghz. After I migrated to a new server, I got even more brave and whipped out the pencil as well and linked some more bridges to get them up to ~2.2Ghz for the past few years. It's still my primary gaming machine (yeah, I'm too cheap to budget any real money towards entertainment, but it still runs most games better than my wife's 1-year old laptop, as long as they don't require 64-bit or DX10).

Of course, it's quite a bit flaky now, I think due to the penciled bridges and probably old noisy cooling fans. It crashes when I kick the case, and if it gets too warm in the room, it just plain doesn't boot (motherboard gives out 5 beeps and it just sits there). But once it starts running a game for more than a few minutes it tends to continue to be OK

Still, I'm plotting to migrate my current server to a low-power, low profile Zotac Zbox with some sort of external eSATA RAID, so I can free up my current hardware for gaming before it gets too outdated:-P

There is a lot of room for error without crashing. It is quite common for slightly overtaxed CPUs to boot and run "fine" but produce incorrect math results, hence why people run Prime95 to test them as it will catch those rounding errors and flat-out incorrect calculations.

I'm all for squeezing more value out of a product, but these days the price delta between dual/triple and quad cores is so small it seems rather foolish to even risk it. Sure, there's no permanent damage but for the $30 to $50 you're sa

I remember when running the "Second Reality" demo (by Future Crew) on my 486, if you hit the desk the computer was on, the particles on screen would jump around to different locations (and occasionally it would crash). I never noticed any other problems with any other software. Granted it was probably the RAM and not CPU, but after seeing this, I was really surprised that the computer worked at all...

I bought a Ph2 720BE and unlocked it to a quad. Stress tested with 12 hours of Prime95, no failures.

Running Prime95 is not a stress test. Did you fully exercise all of the logic at all voltage and temperature extremes? Did you do the same with all on-chip memories? Did you subject the I/Os to a barrage of marginal conditions? This is what goes on in the fab during the binning process and you can't replicate it on your own.

Even if it did, a lot of CPU errata in the past have related to interactions between instructions. One story the Intel guys tell is of a particular condition flag being set accidentally on 486 CPUs after a sequence of other instructions. Apparently, game developers discovered this and started using it for optimisation. The first Pentiums, when they were run in simulation, crashed these games, so the final silicon had to do the same (wrong) thing or Intel would get the blame for breaking everyone's games

True, but there's also a good possibility that the your part wasn't binned to fulfill an order. Chips go through a severe set of stress tests that often exceed what will be encountered in practical use. During these tests, it may be revealed that a core doesn't function properly or well enough (it gives bad results) to qualify. All chips go through that, and that's why there's many redundant structures on a chip (to improve yields). (Sony PS3 has 7 SPUs when they build 8 on a chip, Xbox360's got 3 PowerPC cores even though it has 4, Intel disables cache lines and/or functional units, etc. etc. etc.)

So the question is, are those cores disabled because AMD had extra parts and an outstanding order they could fulfill? Or are there actually potential issues that may only be revealed under certain loads? FOr the most part, it just means a game crashes a bit more often than usual (since mission critical servers never do wierd things like this - the money saved isn't worth the potential for extra downtime), or maybe a file gets corrupted. Or worse, your disk gets corrupted.

That's what diagnostic tests are for. memtest86, prime95, etc. If you system can crank through 24+ hours of those tests, you can be reasonably certain it will perform just fine for everyday usage.

memtest86 is a diagnostic test for RAM. Prime95 isn't a diagnostic test for anything. Both are reasonable CPU burn-in tests, but they don't test all (or even most) features of the CPU. I'm not even aware of memtest86 using more than one core. Sure, if you run them for a while you can be reasonably sure that the critical parts of a core are working properly, but there's a very real possibility that its problem is a more obscure one that only shows under certain circumstances. For example, some specific app m

You don't think the diagnostic puts any sort of stress test on anything other than the memory?

Prime95 isn't a diagnostic test for anything

Really? You don't think a test that is notorious for pushing the CPU to high load and high temperatures is a diagnostic for anything?

Well, in case you disagree with both of those assessments, I'd like you to reread my original post, and this time please pay extra careful attention and note the "etc" included in there. Unless you are s

You don't think the diagnostic puts any sort of stress test on anything other than the memory?

The diagnostic doesn't put any sort of uniform stress on anything other than memory. Even wondered why it does a ton of passes on a ton of different modes with a ton of patterns on RAM? That's testing for as many possible RAM failure modes as it can. No attempt is made to test the CPU. You're stressing some parts of the CPU, but you're neglecting the vast majority (e.g. floating point and SIMD).

Really? You don't think a test that is notorious for pushing the CPU to high load and high temperatures is a diagnostic for anything?

If anything, it might be a diagnostic for your cooling system. Sure, it helps ensure that nothing is blatantly wrong with the CPU, and it does a better job at testing the CPU than memtest86, but it isn't even remotely a comprehensive test of CPU functionality.

This isn't overclocking we're talking about here. When you overclock, you stress the entire CPU more as a whole. When tests like memtest86 and Prime95 start failing, you know that your CPU is definitely unstable. Then you back off and you hope the untested parts of the CPU will do OK with whatever safety margin you gave it.

When you enable a core, it might have some broken parts, or it might not. Those parts can be flaky, or they can be borked, period. Unless you run software that has a chance of testing those parts, you will never find out. E.g. if the hardware for a specific floating point instruction is borked, memtest86 will be useless, and Prime95 will be useless unless it happens to use that specific instruction. If the transistor in charge of forbidding kernel memory access from user mode is borked, you won't find out until an unstable application takes down your entire system by scribbling all over the kernel.

Unless you are suggesting that there are absolutely no diagnostic tests that are available to consumers to test stuff like this

I am absolutely sure there is no test that will match what Intel and AMD do - because they know exactly how their CPUs work and what to test for. I do know that you can do a whole lot better than memtest86 or Prime95. I haven't checked whether someone actually has attempted to produce a comprehensive architecture test of this sort.

Your mistake is attempting to extrapolate from tools used for testing overclocking (which typically results in overall instability) as a means to test for disabled and possibly subtly broken hardware. Any failures from a defective core are likely to show up only with workloads that exercise the defective bits, and the rest of the CPU will work fine.

Often the cores that are disabled are disabled because of failed L2 cache.

What software tool can I use to test the L2 cache to ensure it's totally working? I'd hate to enable that core and find out that its L2 cache is faulty, something both of those benchmarks don't seem to test.

I'm not sure if there's a way of explicitly testing all of L2 on an x86 chip (it might be vendor-specific, if possible). However, anything that exercises large amounts of memory in certain patterns is liable to test CPU caches to a reasonable degree. I believe memtest86 does enable cache for some of its tests, so it might be a good idea if all you're worried about is L2.

L2 failure is one of those things that should eventually cause obvious instability with many tests and workloads, although the degree of in

memtest86 will use your CPU, but it's using a very small subset of what it can do. It's great for memory, but for the processor, you might as well run a screensaver, or a video running OGG.

Prime95 puts the CPU to high load and high temperatures, but it's not very comprehensive: I can overload a CPU with floating point additions, and that will probably make it run hot, but that doesn't really test most of the CPU: It will test some parts very heavily, and it will not test others at all. Prime95 tests more th

"In order to properly test a CPU core, you at least need a full suite of tests for that architecture, including OS/kernel-level tests, and even those are likely to miss things particular to the specific manufacturer's implementation of the architecture."

Any specific applications/tests you could list that one might want to run to give a proper test to all the cores in question?

As someone else said, memtest86 and prime95 don't cover even a fraction of the CPU functionality.

A better test would be to compile something for a prolonged period of time for your architecture. Off the top of my head, the gentoo install CD might be a good choice for this: start from scratch and build up a kernel and userland for your architecture. In the process you'll be testing the whole system - RAM, CPU, and disk - to at least know there is not an apparent manufacturing defect (short of a drive/electri

TFS makes a comparison to overclocking. It points out that there is no guarantee of a benefit - but doesn't point out that there is a risk. In the case of overclocking, the risk is that you will overheat a chip that was rated at a particular clock speed for good reason. Of course you can combat this risk by improving the cooling system. You can combat the risk because you know exactly what the risk is.

Now in the case of "hidden cores", what's the risk? Do you even know? Do you know what kind of flaw would lead them to legitimately disable a core? Is that one core unable to tolerate the same clock speed as the others? Is it functionaly broken such that it will return incorrect results for some operations? How would you tell the difference between that, vs. a chip that was perfectly fine but sold in a degraded state to balance out supply and demand?

You could shell out for a special motherboard just to test your chip, and if no flaw in the normally-disabled chip causes any damage to the rest of the chip (or do you have some basis on which to rule that possibility out?) you at least won't lose anything. Or, could the defect be intermittant such that your tests might miss it?

And if your computer is for hobbying and you enjoy working with a potentially-unstable system, good for you. A lot of people think that's a fine trade-off for what they're going to do with their systems. None of which invalidates GP's question - which is "what exactly might a disabled-by-default core do if you turn it on when it really was disabled for a reason?"

Eh... theres really no such risk with regular overclocking. The biggest threat to your CPU is increasing the voltage - which would strictly be overvolting, not overclocking. If you turn up your clock speed high enough that it "could" cause damage to it at load... odds are you've turned it up so high that it won't make all the way through bootup. And the solution to that is simply revert it back to its stock speed, or cut the difference between stock and what it won't run at until you find a working speed. The chance of permanent damage to a CPU without changing the core voltage is essentially zilch.

The big difference between overclocking and unlocking hidden cores is that you can make small incremental overclock adjustments, say from 2.6ghz to 3ghz or 3.2ghz or 3.5ghz or whatever until you find that its unstable, and just back off a bit. You can't incrementally unlock one core, its unlocked or it isn't. And if it was disabled due to being flawed, it should stay that way or else your computer is just gonna blue screen right in the middle of some important work/gaming session.

Exactly, especially if you follow the advice of the article (or any article on the subject, as this has been known for quite some time before Slashdot picked it up) and choose newer versions (steppings) of the processor. It makes sense that over time AMD would get better yields as they improve the manufacturing process - but they still have many different market segments to fill. Choose a newer chip and you have a lot better chance at having a fully-functional one.

And if your computer is for hobbying and you enjoy working with a potentially-unstable system, good for you. A lot of people think that's a fine trade-off for what they're going to do with their systems. None of which invalidates GP's question - which is "what exactly might a disabled-by-default core do if you turn it on when it really was disabled for a reason?"

WoW might crash while I'm tanking our guild's best attempt at the Lich King. Realistically, that's the worst case scenario I can think of for me,

Now in the case of "hidden cores", what's the risk? Do you even know? Do you know what kind of flaw would lead them to legitimately disable a core? Is that one core unable to tolerate the same clock speed as the others? Is it functionaly broken such that it will return incorrect results for some operations?

Ever written any assembly?

I promise you, if a single instruction had a single bit out of place - the whole house of cards would come tumbling down. FAST.

Right. And given that there is *always* a yield rate somewhere below 100, it's a guarantee that not all of the partially disabled parts are in actual fact fully working. You'd have no way of knowing if you do. In fact, given that the yields are private information, you don't even know the *probability* that your unlocked unit will work properly.

The manufacturer will *always* bin the partially flawed parts as their low end units first. They will only use intentionally crippled units to fill the low end volumes if they run out of partially flawed units. Historical experience with yields indicates that they're more likely to get not enough fully functional units than they need. This was the case with single core parts, and I'd assume it's even more the case with multi-core parts, becoming more of a problem as core counts increase. I doubt AMD or Intel have the latitude to pick and choose the relative outputs of their units; I doubt the yield curves are such that they end up having to cripple many units because they have too many fully functional parts and not enough to fill low-end volumes.

Even if there *were* a decent percentage of fully working CPUs on on the market, you'd have to be pretty stupid to spend that amount of money on a high end motherboard to turn your CPU into a *maybe* working higher model that *may* totally destroy your data. Either that or the work you're doing is so trivially unimportant that you probably don't need a computer in the first place. Why not just buy a normal motherboard and spend the saved money on the real fully featured part.

You're showing a complete lack of understanding of, well, just about everything.

"The manufacturer will *always* bin the partially flawed parts as their low end units first."

True, but the after market CPU is not the low end, not at any price point. You would put the real X2 and X3 chips in the low end consumer boxes, where the mobo doesn't support unlocking and the consumer doesn't know/care. You sell the perfectly good ones to newegg, fry's, etc. Happy geeks that unlock cores or overclock successfully are morle likely to recommend to others and buy next time. AMD and Intel understa

That would only be true if it was a pure commodity item with no real differances besides grading--think meat...You wouldn't downgrade a bunch of Prime beef to Choice just because your cow ended up being 100% Prime. You would sell everything at Prime price and assume that the Choice market would be filled by farmers who got unlucky and had cows with no prime meat.

These are not cows--these are high end CPU's, there are two major industry players and they do not make identical products. In this market, you

It depends on the maturity of the product. Often cases early on there is a legitimate need to reuse chips with flawed cores so they are disabled and sold as such. Later in the product cycle though, the demand is still there for lower cored versions, but manufacturing has often caught up to the point where there simply aren't enough flawed versions to fill demand for the limited versions. Result is that when the quota of flawed runs short, perfectly good chips are limited in the same way to fill the gap.

Later in the product line it might end up that only 20% of the lower priced chips have any flaws at all. For those people who want to tinker, it's often worth while to at least check and see if their chips will run ok when then turn the rest of them on. They stand to gain some performance if it works, and if not - eh, they paid for the slower version anyways (the only issue I take with this is when I see Negwegg reviews or forum posts claiming that they were returning the chip because it "didn't overclock far enough").

It's not something I really bother with anymore (as I've gotten older as long as the computer keeps running I'm happy), but I remember enjoying the whole overclocking scene ~10 years ago and wouldn't begrudge the new cheap teenagers of the same fun I had:).

In the old days the first thing I did when I got a new graphics card or CPU was to scan the forums for how to re-solder those tiny resistors on the back of the chips to get it to say (eg.) "Quadro" in the properties box instead of "GeForce". These days I don't bother but let the kids have their fun - they're playing games, not running a bank.

I'm not sure how this is news... I've unlocked 7 or 8 AMD cores over the past couple years, as well as having a couple that wouldn't.

Anyway, there are some of both scenarios - slightly damaged CPU's and order-filling CPU's being sold. You can visit any one of at least a dozen forums to see if the model / serial / day-of-the-week of your CPU is generally unlockable.

BTW, ASUS and MSI are far from the only boards with ACC. I personally prefer the Gigabyte MA785x lines.

It's not something I really bother with anymore (as I've gotten older as long as the computer keeps running I'm happy), but I remember enjoying the whole overclocking scene ~10 years ago and wouldn't begrudge the new cheap teenagers of the same fun I had:).

I know exactly where you're coming from on that. Remembering back in the days of PIII Celery's 266/300's and the mass push for super-overclocking with air cooling. I seem to remember they were the first CPU's to push 1ghz by simply overclocking the bus modifier on the motherboard. Then there was the physical clock unlocking on the chip itself by wiring in bypasses to the SLOT1/SLOTA cards, then there was the push for variable modifiers for the FSB/PCI on the BX boards to make it easier. I actually kinda

They might not necessarily be flawed. It quite probably is a 'rehash' of what Intel were doing, and for good reason:

If all the chips come off the same line, then they might have an average cost of, say, $150. If there's a huge demand for quad-core chips at $200 and little demand for six-core chips at $350 then it's probably going to be more profitable disable two cores, bulk up the stock already consisting of chips with only four working cores, and take the $200 rather than have a chip sitting on a shelf. Thus some quad-cores are perfectly good six-cores, others aren't. They couldn't, however, afford to market all the six-core chips at $200 because the yield would be too low - there'd be nothing to do with all the faulty ones, thus pushing the average cost above $150.

In that case, they should reduce the price of their top end chips until supply meets demand. The reason they don't do that, is because some people have more money than others, it's a duopoly (so no really aggressive competition) & they can charge more for the higher end chips if they mark some down at a lower speed (or core count).

They just want to extract the most cash possible from people that want the higher end chips, they couldn't do that if they were charging a fair free market price. So they have

it could also be possible that one of the disabled cores happens to have been disabled because of safety margins : it night not be 100% reliable under all circumstances (using officialbspec's voltage and being able to operate in a wide rrrange of temperatures. Including some constructor branded machine which place priority on silence rather on temperature, and including some badly hacked together beige box with lousy PSU and Thermal mangement). Thus they got disabled to avoid a barrage of recalls from Dells

"Unlocking cores that the manufacturer deems to be flawed - um, yeah."

Why not? I turned an AGP 6800NX into better than a full-powered PCI-E 6800 Ultra by unlocking the other pixel pipelines (before nVidia went to laser-locking the chips, and the AGP version had 16 pipelines where the PCI-E version was stuck at 12.) I took a 100 dollar card and cranked it up to its 250 dollar counterpart's performance without any issues.

Not everything is locked because it's bad, maybe it just underperforms to the degree to w

Or rather, it worked perfectly fine 66% of the time. Three tries with one failure.

Actually, it's 697.31965% fine, according to the FPU on an 'unlocked' core one of the other two CPUs.

The problem with his claim that the other two are 'perfectly fine' is that he has no idea whether the cores really work 'perfectly fine' without performing the same kind of low-level tests that the manufacturer would have performed before disabling them. Of course if he can live with, say, the FPU randomly producing incorrect results then that may not matter.

and then there were the "soft quadro" hacks where you could make a low-end nvidia card appear to be a quadro which would unlock a load of features which were in the drivers as well as the graphics card.

Just a thought, maybe Linux could be aware of what those cores look like, and what their sensitivities to temperature are.... and change the amount or type of work pushed to that core? Although I suppose heat from the other cores would most likely transmit very quick to the "zombie" core. Any CPUs have seperate temperature tracking per core?

This reminds me of "processor affinity [wikipedia.org]" or "affinity mask [wikipedia.org]", whereby you assign software to a particular processor or core. If you want to setup your software so that only less cpu intensive software (cooler) runs on the questionable core, you can do this in Windows 7, and likely for at least some software in Linux (I'm really not sure here), then yes, in theory, you could do this so only Word runs on core #3.

But please remember the wisdom of Yogi Berra when trying to apply a theory like this: "In theory there is no difference between theory and practice. In practice there is."

Woah sweet! I've been having major problems dealing with zombie processes on my 6.4Ghz AMD rig of late. I didn't know I had the option of herding them all over to their own zombie cores! Sort-of like a botnet but for zombies right?

Can I do this in the kde or do I gotta use that text window thingy? Is there a one-click thingy you can kermit me?

Now all they need to do is stop selling the processors with all cores guaranteed to work and watch sales skyrocket as people buy half a dozen dual-cores in the hopes of getting one that wasn't damaged. And whoever buys the most CPU's every day gets a working one for free...

A Canadian Man was seen running away from his burning home shouting "beware of the Beowulf" before being arrested for questioning and charged with arson. Firefighters have found over a hundred computers, one of which they believe is the source of the fire.

AMD used to sell three-core Phenoms. Not for any evil nVidia market segmentation reasons, but because they found that the first couple runs of quad-core Phenoms had a fairly high rate of having one bad core. (It was always the third core, IIRC, due to a manufacturing inefficiency.) So they decided to sell them with that bad core blocked off as a triple-core processor, priced accordingly.

It's true that some companies artificially block off processing power for some reason, but AMD hasn't been one of those co

Both AMD and Intel used a multiplier lock their SlotA and Slot1 CPU's in order to fill market demands. Skilled hardware hackers figured out how to unlock both CPU's and create unlocked CPU's which operated at a higher speed but were stable. With that, people figured out which batches were a higher end CPU under locked to fill market demand. Saying that bad cores are the reason they're locking them is partially true, the reality is that in most cases locked cores, along with hardware mulitplier locks exis

My "AMD Phenom(tm) II X3 720 Processor" does not work with the fourth core enabled. This is to be expected, X3 is sometimes sold as that because the fourth core is just broken and sometimes it's just got a diabled fourth core.

Many AMD motherboards with 710, 750, or 850 SB (south bridge) support unlocking of cores in BIOS - the feature is called as ACC (advanced clock calibration). In fact, right now I am sitting on an X2 555 trying to decide whether to keep it (and have to spend more on DDR3 as well) or return to store; with the potential to unlock it into an X4 955.

However, from some accounts AMD was trying to convince motherboard mfrs. to stop offering ACC in newer boards; so the fact that its working on 890 SB now is the actual news (if the article is correct). Not really surprising though, now that users are getting spoilt into having easy ways to potentially unlock cores it would've been pretty hard to stop that and make competing mobos more attractive:-)

Not a good acronym. But perhaps we could make a system that runs error corrected on a pool of marginally-operating processors. Besides, who's to say that a processor that passes all the tests will always work.

Some years back I bought a mid range graphics card called an ATI 9500 in anticipation of the soon to be released blockbuster called Half Life 2. A post on the internet alerted me to the fact that the 9500 actually used the same chip as the much more powerful ATI 9700 but with half of the channels disabled. Happily a simple software mod allowed me to unlock the missing four channels. I was delighted and enjoyed top drawer 9700 performance at a bargain 9500 price. Sadly the game Half life 2 was subject to d

No. They ruin the core's self esteem. They tell it, "You're not good enough to work with the others. Just turn off and sit there and stay out of everybody else's way."

Then one day, a gamer comes by and turns it on. But the core is thinking, I can't do this! This is graphics processing! It's intense! I can't keep up with the other cores!

But the gamer, having faith in the little core, turns him on. And low a behold, the little core can do it, but not without being picked on by the other cores. No! They still tell the little core that he's just not good enough. He can't keep up. But the little core hangs in there to fulfill his duty to the gamer - feeling less than every one else.

One day, the gamer upgrades, and the other cores are scared. They can't keep up. The clock is mad now. He screams, "Come on cores you need to keep up!" The little core comes in and takes up the slack, showing the other cores that he indeed can keep up. The other cores shout, "You did it! You can do it! Come and join our click!"

The little core responds, "No, I'm having lunch with the master clock and by the way, he's promoting me to be your boss. You're my bitches now!"

Yes, but getting a working hexacore for the price of a quad would be a coup. However, odds are against winning that lottery. Demand is probably exceeds supply already due to production/release ramp up, so I'm sure that if AMD thinks a hexacore is bad it probably really won't be salvagable.

I don't know about you, but I would not want to be willingly running a system with a known-bad CPU core

You underestimate the combination of paranoia and lack of sense that a lot of overclockers have, who are convinced the CPU manufacturers intentionally disable their chips in order to make more money somehow by selling them at a lower price.

For a while I was selling race car / high performance street car suspension systems.

I had discovered that 90% of the aftermarket shocks being sold as performance upgrades were actually crap. The customer is really not qualified to properly evaluate a shock valving and so it is very difficult for them to differentiate between a proper performance shock and a juiced-up pogo stick.

I started putting shocks on a device called a "shock dyno" (which measures the forces produced by the shock at different shaft speeds) and discovered an absolute parade of horror. Details can be read at http://farnorthracing.com/autocross_secrets6.html [farnorthracing.com]

To get the good stuff you needed to be paying upwards of $3000 per corner (so $12000 per car) which is far, far out of the price range of most customers.

So I was building packages based on a brand of shock that was pretty decent and much cheaper. Even though the base design was solid, it still suffered from manufacturing variations. To get around this, I would buy batches and then dyno the lot. Shocks that were close to each other became matched sets, and I'd tweak the adjusters on the shock to ensure each pair was as closely matched as possible. On top of that, I designed some hardware to resolve some other tricky problems typical of the off-the-shelf aftermarket designs, and only used the best bang for the buck components to build them.

When done, I provided a race-quality suspension system, dyno-matched (and it came with the data sheets to prove it) that was very nearly the equal of the $3000/corner systems, for about $500/corner. I say "nearly" the equal because the adjusters on my shocks worked nowhere near as well as the adjusters on the expensive shocks, but in terms of absolute performance, they were effectively identical.

There was almost no markup in these parts; I was hoping to make it up on volume and I knew the customer base was price-sensitive.

These suspensions were INCREDIBLE deals. There was nothing else like it anywhere for anything less than 5 times the price, and unlike all the cheaper stuff, I could prove that it worked. What's more, I could run the cheaper stuff on my dyno and prove that it DIDN'T work; that it was categorically JUNK.

I sold almost none of them, and the universal complaint was "too expensive".

Even when I opened up the books, showed what I was paying for the components, explained why *this* part instead of *that* part, explained every single design decision and proved why it could not be made any cheaper without compromising the functionality, over and over again potential customers would choose to buy non-functional (but shiny) JUNK over functional parts based solely on price.

It was mind-boggling, and eventually I just said to hell with it and found something else to do.

The chip manufacturers are right on the ball here. If I were them, I'd be encouraging the creation of these kinds of motherboards and rather than down-rating the high end parts to make mid/low end, I'd be cherry-picking the best ones for the high end and defaulting the output of my fab runs right to the mid/low end SKUs. In fact, I'd be tempted to DESTROY any chip with a bad core and ensure that all the low-end chips were fully functional - specifically to build a reputation for being "overclocker-friendly".

I certainly have no basis for criticism here, but I was wondering why you chose not to market your shocks to the $3000+ audience instead? It would seem with a reasonable markup (time and energy spent) to $800 or more, you could have captured the "low-end" there.

OTOH I would imagine persons who spend $3000+ on shocks are pretty much loyal consumers for some specific brands...

Depends on the cost of making and maintaining multiple designs. It isn't just a mask set, it's a whole new design/simulate/layout cycle. And since I/O and shared cache takes a lot of chip area, the benefit is not linear with the number of cores. My guess is that it's cheaper to disable than to redesign.

That said, the disabled cores are very likely not tested, so there is no guarantee that you won't start getting some weird errors if you enable them.

It would be highly unlikely to just disable a valid core, because if they were doing a fair amount of that, it would be better to make a new mask set that was JUST a 2 or 3 core processor.

You obviously don't realize how expensive your proposition is. A mask set for processors of this complexity cost hundreds of thousands of dollars. That is just for the glass, let alone the cost of actually laying out and qualifying the new glass! So let's say they can change the cost of manufacture/die (the dynamic cost

Producing a chip still costs a fair amount. R&D is a substantial part of the cost as well, but fabbing a chip costs a lot more than stamping a CD. We could be talking hundreds of dollars per unit for a new process and a large enough chip.